Carbon dioxide (CO2) may be harmful to the earth's atmosphere in large quantities. The separation of CO2 from a mixed-gas source (such as the atmosphere) may be accomplished by a capture and regeneration process. The process generally includes a selective capture of CO2, accomplished by, for example, contacting a mixed-gas source with a solid or liquid adsorber/absorber followed by a generation or desorption of CO2 from the adsorber/absorber. One technique describes the use of bipolar membrane electrodialysis for CO2 extraction/removal from potassium carbonate and bicarbonate solutions.
For capture/regeneration systems, a total volume of mixed-gas source that must be processed is generally inversely related to a concentration of CO2 in the mixed-gas source, adding significant challenges to the separation of CO2 from dilute sources such as the atmosphere. CO2 in the atmosphere, however, establishes equilibrium with the total dissolved inorganic carbon in the oceans, which is largely in the form of bicarbonate ions (HCO3−) at an ocean pH of 8.1-8.3. Therefore, a method for extracting CO2 from the dissolved inorganic carbon of the oceans would effectively enable the separation of CO2 from atmosphere without the need to process large volumes of air.